Note: Descriptions are shown in the official language in which they were submitted.
~53~
TITLE
HYDRAULICALLY POWERED MARINE PROPULSION TILTING
SYSTEM WITH AUTOMATIC LET-DOWN ASSEMBLY
INVENTOR
CHARLES B. HALL
S RELATED APPLICATION
: : .
` Attention is directed to United States Patent ~-
i 3,983,835 issued October 5, 1976.
BACKGROUND OF THE INVENTION
The invention relates generally to marine propulsion
devices such as outboard motors and stern drive units. ~ ~
The invention also relates to arrangements for ~ ;
tilting and trimming the propulsion assemblies of such
marine propulsion devices.
The invention further relates to hydraulically :
' 15 operated trimming and tilting arrangements for the propulsion
i assemblies of such marine propulsion devices.
~ Attention is directed to the following prior United
t States Patents~
1 Carpenter 3,722,455 issued March 27, 1973
Shimanckas 3f847,198 issued November 12, 1974 .
Borst 3,863,592 issued February 4, 1975 ,"
Borst 3,885,517 issued May 27, 1975 `~~ SUMMARY OF THE INVENTION ~ -
`l~ The invention provides a marine propulsion device
., 25 including a member adapted to be attached to a boat hull, a
.; ,. . .
~ propulsion assembly pivotally connected to the member for
.l vertical swinging movement when the member is attached to the
i boat hull, a tilt hydraulic cylinder piston assembly connected `
~ between the member and the propulsion assembly and including a :~
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- tilt cylinder having opposed first and second ends,
. pressure fluid supply and control means including a ~ .
control valve housing having first and second ends,
first conduit means communicating between the first end
of the tilt cylinder and the first end of the control
valve housing and including a first valve preventing
.I fluld flow from the first end of the control valve
housing to the first end of the tilt cylinder and
releasably preventing fluid flow from the first end of
the tilt cylinder to the first end of the control valve
housing, and second conduit means communicating between
the first end of the tilt cylinder and the first end of
the control valve housing and including a second valve
preventing fluid flow from the first end of the tilt
cylinder to the first end of the control valve housing
and releasably preventing fluid flow from the first end
of the control valve housing to the first end of the
tilt cylinder, and a normally closed third valve located
' between the first end of the control valve housing and
the first conduit means and arranged to releasably
prevent fluid flow therethrough to and from the first ~ :
end of the control valve housing.
The invention also provides for a marine
propulsion device including a member adapted to be
. 25 attached to a boat hull, a propulsion assembly pivotally~ r
` connected to the member for vertical swinging movement
when the member is attached to the boat hull, a tilt -
hydraulic cylinder-piston assembly connected between
the member and the propulsion assembly and inlcuding a
. 30 tilt cylinder having opposed ends, a control valve
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adapted to co~municate with a source of pressure fluid,
first conduit means communicating between one of the
ends of the tilt cylinder and the control valve and
including a first valve preventing fluid flow from the
control valve to the one end of the tilt cylinder and
releasably preventing fluid flow from the one end of
the tilt cylinder to the control valve, and second
conduit means communicating between the one end of the
tilt cylinder and the control valve and including a
second vlave preventing fluid flow from the one end of
the tilt cylinder to the control valve and releasably
preventing fluid flow from the control valve to the one
end of the tilt cylinder, and a normally closed third
valve located between the control valve and the first
. 15 conduit means and arranged to releasably prevent fluid
`~ ~low through the first conduit means to and from the
control valve and independently of the second valve. .
The invention also provides a marine propulsion
device including a member adapted to be attached to a
20 boat hull, a propulsion assembly pivotally connected to ~: ~
the member for vertical swinging movemen~ when the ; .
member is attached to the boat hull, a tilt hydraulic ~ .
cylinder-piston assembly connected between the member
and the propulsion assembly and including a tilt cylinder ;. .
, 25 having opposed ends, a trim hydraulic cylinder-piston ~.
assembly including a trim cylinder fixed relative to
one of the member and the propulsion assembly, having
. opposed first and second ends, and having therein a . :
reciprocably movable trim piston having a piston rod -
30 extending through the second end of the trim cylinder -~
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and adapted for releasable engagement with the other of
the member and the propulsion assembly, a control valve
adapted to communicate with a source of pressure fluid,
first conduit means communicating between one of the
ends of the tilt cylinder and the control valve and
inlcuding a ~irst valve preventing fluid flow from the
control valve to the one end of the tilt cylinder and
releasably preventing fluid flow :Erom the one end of
the tilt cylinder to the control valve, second conduit
means communicating between the one end of the tilt
cylinder and the control valve and including a second
valve preventing flow from the one end of the tilt
cylinder to the control valve and releasably preventing
fluid ~low from the control valve to the one end of the
tilt cylinder, and third conduit means communicating
between the first end of the trim cylinder and the con- ~:
trol valve.
The invention also provides a marine propulsion
device including a member adapted to be attached to a
20 boat hull, a propulsion assembly pivotally connected to -
the member for vertical swinging movement when the : :~
member is attached to the boat hull, a tilt hydraulic ~:.
cylinder-piston assembly connected between the member ~:: :- ;
.
and the propulsion assem~ly and including a tilt cylinder ::.
25 having opposed first and second ends, a trim hydraulic :: -
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cylinder-piston assembly including a trim cylinder j : .
fixed relative to one of the member and the propulsion
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assembly, having opposed first and second ends, and : . :
having therein a reciprocably movable trim piston : :-
30 having a piston rod extending through the second end of '~
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the trim cylinder and adapted for releasable engagement
with the other of the member and the propulsion assembly,
pressure fluid supply and control means, first conduit
means communicating between the first end of the tilt
cylinder and the pressure fluid suppl.y and control
means and including a first valve preventing fluid flow
from the pressure fluid supply and control means to the
first end of the tilt cylinder and releasably preventing
fluid flow from the first end of the tilt cylinder to
the pressure fluid supply and control means, second
conduit means communicating between the first end of
the tilt cylinder and the pressure fluid supply and
control means and including a second valve preventing
flow from the first end of the tilt cylinder to the
15 pressure fluid supply and control means and releasably -: -
preventing fluid flow from the pressure fluid supply .
and control means to the first end of the tilt cylinder,
i and third conduit means communicating between the first
j end of the trim cylinder and the first conduit means ~ .
: 20 intermediate the pressure fluid supply and control
:~ means and the first valve.
A marine propulsion device including a member . ~
adapted to be attached to a boat hull, a propulsion :
` assembly pivotally connected to the member for vertical
" .
, 25 swinging movement when the member is attached to the
boat hull, a tilt hydraulic cylinder-piston assembly
. connected between the member and the propulsion assembly ~ -
: and including a tilt cylinder having opposed ends, a ~
trim hydraulic cylinder-piston assembly including a .
30 trim ~ylinder fixed relative to one of the member and
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the propulsion assembly, having opposed first and
second ends, and having therein a reciprocably movable
trim piston having a piston rod extending through the
second end of the trim cylinder and adapted for releasable
engagement with the other of the member and the propulsion
assembly, a control valve housing adapted to communicate
with a source of pressure fluid and having first and
second ends, first conduit means communicating between
one of the ends of the tilt cylinder and the first end
of the control valve housing and including a first
valve preventing fluid flow from the housing to the one : .
end of the tilt cylinder and releasably preventing . :
fluid flow from the one end of the tilt cylinder to the
control valve housing, second conduit means communicating .:. .
15 between the one end of the tilt cylinder and the first :
end of the control valve housing and including a second
valve preventing flow from the one end of the itlt
cylinder to the control valve housing and releasably :~:
:
preventing fluid flow from the control valve housing to ~:
20 the one end of the tilt cylinder, third conduit means
communicating between the one end of the trim cylinder
and the first end of the control valve housing, a :~
normally closed third valve connected between the first
end of the control valve housing and the first and -.
25 third conduit means and arranged to releasably prevent
fluid flow therethrough to and from the control valve : -
housing, and a normally closed fourth valve connected 5:
. between the second end of the control valve housing and . .
the other of the ends of the tilt cylinder and the ::
30 second end of the trim cylinder and arranged to releasably :.
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prevent flow therethrough to and from the control valve
housing.
The invention also provides a marine propulsion
device including a member adapted to be attached to a
boat hull, a propulsion assembly pivotally connected to
the member for vertical swinging movement when the
member is attached to the boat hull, a tilt hydraulic
cylinder-piston assembly connected between the member
and the propulsion assembly and including a tilt cylinder
having opposed first and second ends, a trim hydraulic
cylinder-piston assembly including a trim cylinder
fixed relative to one of the member and the propulsion
assembly, having opposed first and second ends, and
having therein a reciprocably movable trim piston :
15 having a piston rod extending through the second end of :~
the trim cylinder and adapted for releasable engagement : :
with the other of the member and the propulsion assembly,
pressure fluid supply and control means including a
control valve housing having first and second ends,
first conduit means communicating between the first end
'~ of the tilt cylinder and the first end of the control -
valve housing and including a first valve preventing
fluid flow from the pressure fluid supply and control
means to the first end of the tilt cylinder and releasably
25 preventing fluid flow from the first end of the tilt .
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cylinder to the first end of the control valve housing,
- second conduit means communicating between the first
~ end of the tilt cylinder and the first end of the
:, control valve housing and including a second valve
preventing flow from the first end o the tilt cylinder
to the irst end of the control valve housing and
releasably preventing fluid flow from the first end of
the control valve housing to first end of the tilt
cylinder, third conduit means communicating between the
first end of the trim cylinder and the first end of the
, control valve housing, a normally closed third valve
:` located between the first end of the control valve
'' housing and the first and thrid conduit means and
~ arranged to releasably prevent fluid flow ther~through
`~ 15 to and from the first end of the control valve housing,
a normally closed fourth valve communicating between
~,~ the second end of the control valve housing and the
, second end of the tilt cylinder and the second end of
the trim cylinder and arranged to releasably prevent
~ 20 flow therethrough to and from the second end of the
`. control valve housing.
; The invention also provides a marine propulsion
: device including a member adapted to be attached to a
boat hull, a propulsion assembly pivotally connected to
,~ 25 the member for vertical swinging movement when the
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member is attached to the boat hull, a tilt hydraulic
cylinder-piston assembly connected between the member
and said propulsion assembly and including a tilt
cylinder having opposed ends, a control valve adapted .
to communicate with a source of pressure fluid, first `
conduit means communicating between one of the ends of
the tilt cylinder and the control valve and including a
first valve preventing fluid flow from the control ~
valve to ~he one end of the tilt cylinder and releasably
preventing fluid flow from the one end of the tilt
cylinder to the control valve, second conduit means
communicating between the one end of the tilt cylinder
and the control valve and including a second valve
preventing flow from the one end of the tilt cylinder
15 to the control valve and releasably preventing fluid -
flow from the control valve to the one end of the tilt
cylinder, and a normally closed relief valve communicating :~
between the second conduit means and a sump and arranged
to afford fluid flow from the second conduit means in
. 20 the event of a pressure therein above a pre-determined :
level. : ,
The invention also provides a marine propulsion
.
device including a member adapted to be attached to a
boat hull, a propulsion assembly pivotally connected to
the member for vertical swinging movement when the
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member is attached to the boat hull, a tilt hydraulic
cylinder-pis~on assembly connected between the member
and the propulsion assembly and including a tilt cylinder
having opposed first and second ends, pressure fluid
supply and control means, first conduit means communica-
ting between the first end of the tilt cylinder and the
pressure fluid supply and control means and including a
first valve preventing fluid flow from the pressure
fluid supply and control means to the first end of the
tilt cylinder and releasably preventing fluid flow from
the first end of the tilt cylinder to the pressure
fluid supply and control means, second conduit means
communicating between the first end of the tilt cylinder
and the pressure fluid supply and control means and
including a second valve preventing flow from the first
end of the tilt cylinder to the pressure fluid supply
and control means and releasably preventing fluid flow
from the pressure fluid supply and control means to the
~` first end of the tilt cylinder, and a normally closed
relief valve communicating between the second conduit
means and a sum~ and arranged to afford fluid flow from
the second conduit means in the event of a pressure
therein above a predetermined level.
The invention also provides a marine propulsion
device including a member adapted to be attached to a
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boat hull, a propulsion assembly connected to the
member for vertical swinging movement relative thereto,
a hydraulic cylinder-piston assembly connected to the
member and to the propulsion assembly and including a
tilt cylinder having opposed first and second ends, a
piston reciprocable in the tilt cylinder, and a piston
rod connected to the piston and extending from the
second end of the tilt cylinder, and means communicating
between the first and second ends of the tilt cylinder
and including means operative for temporarily affording
fluid flow from the first end of the tilt cylinder to
the second end of the tilt cylinder in response to the ~ ;
generation of relatively high pressure adjacent the
second end of said tilt cylinder occurring incident to -
the striking of an underwater obstacle.
Other features and advantages of the embodiments
of the invention will become apparent from the following
` general description, claims and appended drawings. ~ ~ .
.. . .
THE DRAWINGS ~
,
Figure 1 is a partially schematic side- :
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elevation view, partially in section, of a marine -
propulsion device incorporating various of the features
of the invention.
~,; Figure 2 is a schematic diagram of the hydraulic
system incorporated in the marine propulsion device
` shown in Figure 1.
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Before explaining the embodiments of the invention
in detail, it is to be understood that the invention is not
limited in its application to the details of construction and
the arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments and of being practiced and carried
out in various ways. Also it is to be understood that the
phraseology and terminology employed herein is for purpose of
description and should not be regarded as limiting.
GENERAL DESCRIPTION
Shown in the drawings is a marine propulsion device
which is shown schematically in the form of an outboard motor
11 including a member 13 adapted to be suitably attached to a
boat hull 15, and a propulsion assembly 17 connected to the
member 13 for vertical swinging movement between a fully lowered
position and a fully raised position when the member 13 is
connected to the boat hull 15. Any suitable form of propulsion
assembly can be employed, including, for instance, a swivel
bracket 19 connected to the member 13 about a horizontal tilt
~` 20 pin 21 and a propulsion unit 23 connected to the swivel bracket
13 for steering movement relative thereto. The invention is
equally applicable to stern drive units and to outboard motors.
Connected between the member 13 and the propulsion
assembly 17 is (See Fig. 2) a hydraulic system 25 for tilting
~, 25 and trimming the propulsion assembly 17 relative to the boat
mounted member 13. As used herein, "trimming" refers to angular
~; adjustment or movement within a trim range extending up and
.
from the fully lowered position of the propulsion assembly 17
, and "tilting" refers to angular adjustment or movement within
~ 30 a tilt range extending upwardly from the top of the trim range
`~- ' to the fully elevated or raised position of the propulsion
assembly 17. ~;
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The hydraulic system 25 includes one or more trim
and tilt hydraulic cylinder-piston assemblies 31 and 33, re-
spectively J which are connected between the member and the
propulsion assembly. More particularly, the tilt cylinder-
piston assembly 33 comprises a tilt cylinder 35 which has `
opposed first and second ends 37 and 39, respectively, which, .;
: at its irst end 37, is pivotally connected to one of the ~' ,'
member 13 and the propulsion assembly 17, and which contains
a tilt piston 41 connected to a piston rod 43 which exte~ds '
through the second tilt cylinder end 39 and is pivotally
connected to the other of the member 13 and the propulsion
assembly 17. Preferably, the tilt cylinder-piston assembly is
I connected between the member 13 and the swivel bracket 19 and `.~
' the first end 37 of the tilt cylinder 35 is pivotally connected '''
` 15 to the member 13 and the piston rod 43 is pivotally connected ';`
'. to the swivel bracket 19. ..
The trim cylinder-piston assembly 31 comprises a trim :'~; '
cylinder 45 which has opposed first and second ends 47 and 49, '
respectively, which is fixed to one of the member 13 and the ... :'~
' ~0 propulsion assembly 17 and which includes a trim piston 51 con- .
, nected to a piston rod 53 which extends through the sècond end
'~:! 49 of the trim cylinder 45, and which is releasably engagable withr~ the other of the member 13 and the propulsion assembly 17. Pre-
ferably, the trim cylinder 45 is fixed to the member 13 and the :
'' 25 piston rod 53 is releasably engagable with the swivel bracket 19. ~
Located in the tilt piston 41 is a one way valve 61
which is in the form of a spring kiased ball check valve and
which prevents flow from the first end 37 of the tilt cylinder ~` '
35 to the second end 39, but which permits flow from the second ;
l~l 30 end 39 of the tilt cylinder 35 to the first end 37 of the tilt ~'.
.. ~ cylinder 35 so that, in the event the propulsion assembly 17 ~
'~ impacts an underwater obstacle and the tilt cylinder 35 accord- ' .
ingly extends rapidly, the valve 61 will accommddate'flow 'from ' '
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the second end 39 of the tilt cylinder 35 through the tilt ~ :
piston 41 to the first end 37 of the tilt cylinder 35. The
bias on the valve 61 is relatively high, for instance, about
2500 lbs./sq. in.
Pressure fluid supply and control means are provided
~or selectively supplying the trim and tilt cylinder-piston
assemblies 31 and 33 with pressure ~luid. While various means
can be employed, in the illustrated construction, such means
comprises a reservoir or sump 71, a pump 73 operably connected
to the sump 71, a control cylinder or valve 75 connected to the
pump 73, and valved fluid conduits communicating between the
control valve 75 and the tilt and trim cylinders 35 and 45.
More specifically, the pump 73 i5 in the form of a
reversible pump which includes two fluid connections or ducts
77 and 79 with the duct 77 supplying pressure fluid when the
pump 73 is rotating in one direction and with the other duct
79 supplying pressure fluid when the pump 73 is running in the
opposite direction. The ducts 77 and 79 are respectively con-
nected through conduits 81 and 83 with the reservoir 71. In
turn, the conduits 81 and 83 include respective one-way valves ~`
, 87 and 89 permitting flow to the.pump 73 and preventing flow .
Y, to the reservoir 71. Preferably, the conduits 81 and 83 com- .
, municate with the sump or reservoir 71 through a common filter 91.
:;~ The control valve 75 comprises a housing 93 which has
opposing first and second ends 95 and 97 which respectively
~' communicate with the ducts. The housing 93 also includes therein
~, a control piston 99 movable from a centered position to each of' .
¦ first and second end positions respectively adjacent to the first
~ and second ends 95 and 97 of the housing 93 so that the first .:.:
.,~ 30 end 95 of the housing 93 is pressurized when the pump 73 is ro~
~ , . . . .
~ tating in one direction and so that the second end 97 of the :
I housing 93 is pressurized when the pump 73 is rotating in the ! ~'.,,
other direction.
Communicating with the second end 97 of the control : :
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valve housing 93 is a spring biased, normally closed valve 111
which also communicates through respective conduits 113 and
115 with the second end 49 of the trim cylinder 45 and with
the second end 39 of the tilt cylinder 35. Communicating
with the first end 95 of the control valve housing 93 is another
spring biased, normally closed valve 121.
Means are provided on the control piston 99 in the
~orm of oppositely extending projections 123 and 125 for re-
spectively opening the valves 121 and 111 when the control
piston 99 is located in the first and second end positions.
More specifically, when the first end 95 of the control valve
housing 93 is pressurized, the projection 125 opens the valve
111 to permit fluid flow into the housing 93 and when the
second end 97 of the control valve housing 93 is pressurized,
the projection 123 opens the valve 121 to permit inflow of `~
fluid from the respective first ends of the tilt cylinder 35
, and trim cylinder 45.
When the pump 73 is not operating, the control piston
' 99 is located in its centered position and both valves 111 and
`, 20 121 are closed by their respective springs.
The valve 121 communicates directly with the first
end 47 of the trim cylinder 45 through a conduit 131.
The valve 121 also communicates with the first end
~, 37 of the tilt cylinder 35 through a conduit 133 including a
'l 25 normally closed valve 135 which is in the form of a spring :
biased one-way valve, which prevents 10w from the valve 121
to the first end 37 of the tilt cylinder 35, but which
releasably prevents or permits flow from the first end 37 of the
' tilt cylinder 35 to the valve 121.
Also communicating with the first end 37 of the tilt
~; cylinder 35 is an~ther conduit 137 which extends from adjacent
to the first end 95 of the control valve housing 93 and which
includes a normally closed valve 139 which is in the form of a
' spring biased one-way valve, which prevents flow from the first
.
end 37 of the tilt cylinder 33 to the control valve housing 93,
but which releasably prevents or permits flow from -the first
end 95 of the control valve housing 93 to the first end 37 of
the tilt cylinder 33 independently of the check valve 135.
The hydraulic system 25 also includes let-down means
~ providing automatic transfer of pressure fluid from the first end
i; 37 of the tilt cylinder 35 to the second end 39 of the tilt cylinder
35 in order to acco~modatelet-down of the propulsion assembly 17
after the s~riking of an underwater obstacle. More particularly,
there is hydraulically connected between the ends 37 and 39 of
the tilt cylinder 35 an automatic let-down assembly 151 which in-
cludes an actuating valve 153 which is in the form of a normally
,, .
,~ closed spring biased check valve, and which communicates through
a conduit 154 with the second end 33 of the tilt cylinder 35 and
1 ,
which is arranged to prevent flow to the second end 39 of the tilt
cylinder 35 and to releasably prevent or permit flow from the second
.
; end 39 of the tilt cylinder 35 therethrough. The bias on the valve
153 is relatively high, for instance, about 2500 lbs./sq.in.
~' Also included in the let-down valve assembly 151 is a
`-; 20 let-down valve 155 including a housing 157 having a first end 159
" .
' communicating with the valve 153 and a second end 161 communicating
~- with a by-pass valve 163 which is in the form of a normally closed :
; spring biased check valve and which, in turn, communicates through ~ -
i a conduit 165 with the first end 37 of the tilt cylinder 35. The
; 25 bias on the valve 163 is relatively low, for instance, about
25 lbs./sq. in.
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-~l Located within the let-down valve housing 157 is a -
,~ let-down piston 171 which is movable between a first position
,~Z adjacent to the first end 159 of the let-down valve housing 157
`~ 30 and a second position spaced from the first position in the
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' direction toward the second end 161 of the let-down valve housing
, 157. The let-down piston 171 includes a restricted orifice or
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slot 172 which com~unicates between the first^and second ends
~ of the let-down valve housing 157. In addition, the let-down
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piston 171 also includes a projection 173 which is operable,
upon movment of the piston 171 to the second position, to open ~ -
the valve 163 so as to permit fluid flow from the first end 37
of the tilt cylinder 35 into the let-down valve housing 157.
Comm~micating between the second end of the let-down
valve housing 157 and the second end 39 of the tilt cylinder 35 .
i9 conduit means including a conduit 175 extending from adjacent
the second end 161 of the let-down valve housing 157 to the sump
71, and a conduit 177 extending from the sump 71 to the second
end 39 of the tilt cylinder 35 and including a one-way valve 179
preventing flow to the sump 71 and permitting flow from the sump 71.
The hydraulic system 25 also includes an overload
valve 191 which communicates between the conduits 165 and 175
and which is in ~he form of a normally closed spring biased
check valve arranged so as t~permit flow from the conduit 165
to the conduit 175 and to prevent flow from the conduit 175 to
the conduit 165 and hence from the first~na 37 of the tilt
cylinder 35 to the sump 71 in the event ~xcess thrust is devel-
oped during operation of the propulsion assembly 17. In addi-
tion, when the control piston 99 is in the position providing
i power operated upward movement of the propulsion assembly 17,
-~ the overload valve 191 prevents overloading of the pump 73 by
permitting bypassing of the pressure fluid to the sump 71 when~
ever movement of the trim piston 51 or tilt piston ~1 is blocked,
or when the propulsion assembly 17 is in the fully raised posi-
tion. It is noted that the spring bias on the valve 191 is
greater than the spring bias on the valve 139 and greater than :~:
the spring bias on the valve 135.
~ When the control piston 99 is in the position providing :
:~ 30 power operated downward movement, the valve 135 permits return
I flow from the first end 37 of the tilt cylinder 3S to the
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valve 121 and then through the control valve housing 93 and
back through the duct 79 to the pump 73.
The hydraulic system 25 also includes a pressure
relief valve 193 which communicates with the sump 71 through
a conduit 195 which communicates with the second end 97
o:E the control valve housing 93, and which is operative to
permit 10w from the second end 97 of the control valve housing
93 to the sump 71 in the event of excess pressure when the t
; control piston 99 is in the position providing power operated
lowering of the propulsion assembly. In addition, the relief
~alve 193 also operates, when the control piston 99 is in :
the position affording power operated raising of the propulsion
assembly 17, to prevent the relatively high pressures resulting
from impact or shock absorption from adversely affecting the
pump 73. The pressure relief valve 193 is preferably in the
form of a normally closed, spring biased check valve and has
a spring bias which is greater than the valve 111. .. .
The hydraulic system 25 also includes a conduit 197 .~
which connects the opposed ends 37 and 39 of the tilt cylinder `~:
35 and which includes a manually operable va-lve 199 permitting .
bypass of fluid around the tilt piston 41 to accomodate manual .; ;
raising and lowering of the propulsion assembly 17. ;
In operatio.n and when it is desired to raise the
propulsion assembly 17 by power operation, the pump 73 is . .
operated in the proper direction to pressurize the first end ~.:
- 95 of the control valve housing 93 so as to displace the control .. :
. piston 99 toward the end 97 of the control valve housing 93, :.
- thereby opening the adjacent valve 111. At the same time, the .~
pump pressure opens the other valve 121 against its spring to . ..
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~ 30 supply pressure fluid through the conduit 131 to the first end ::
- 47 Q~.the t~im.cylinder 45. :In.addit,ipn, pressure fluid flows ~ . :
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53~)~3
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throu~gh the conduit 137 and through the valve-:139 to ~he ~irst `~
end 37 of the tilt cylinder 35.
At the same time, pressure fluid adjacent to the
second end 39 of the tilt cylinder 35 and pressure fluid
adjacent to the second end 49 of the trim cylinder 45 flows
through the conduits 113 and 115 past the open valve 111
through the second end 97 of the control valve housing 93
and through the duct 77 to the intake of the pump. Make-up
fluid is drawn from the sump 71 through the conduit 81 and
through the check valve 87.
In the event there is an obstruction to upward travel
. of the propulsion assembly 17 or at the end of such travel, the
- pressure fluid supplied by the pump 73 flows back to the sump
71 ~hrough the conduit 137 including the valve 139, through the
.- 15 conduit 165, and through the overload valve 191 which operates ..
as a pressure relief valve, and through the conduit 175 to the
sump 71.
.i . . .
During power operated lowering of the propulsion : .
assembly 17, the pump 73 is operated in the opposite direction, ~ :
and serves to deliver pressure fluid through the duct 77 to the
. second end 97 of the control valve housing 93, thereby opening '.:
the adjacent valve 111 and displacing the control piston 99 to .
... . .
. the position adjacent the first end 95 of the control valve :-.
~, housing 93 so as to also open the valve 121. Pressure fluid ~ .
flows through the valve 111 and through the conduit 113 to the
second end 49 of the trim cylinder 45 so as to retract the
`. piston rod 51 and through the conduit 115 to the second end 39
of the tilt cylinder 35 to contract the tilt cylinder-piston : - -
assembly 33. At the same time, fluid adjacent the first end
37 of the tilt cylinder 35 flows through the conduit 133, in- -
, cluding the valve 135, and past the open valve 121 to the end .:
95 of the control valve housing 93, then through the duct 79 to
..
S ,': ' '
1~53~
~he inlet of the pump 73. If there is an obstruction to
movement of the propulsion assembly 17, or at the end of
such movement when the propulsion assembly 17 is in the t
fully lowered position, pressure fluid produced by the pump
573 is returned to the sump 71 via the pressure relief valve
193 through the conduit 195. Fluid is supplied to the pump
73 from the sump 71 for priming purposes through the conduit
83 and check valve 89.
In the event the propulsion assembly 17 strikes an
10underwater obstacle, sudden upward movement of the propulsion
assembly 17 will cause extension of the tilt cylinder 35 and
consequent immediate relatively high pressurization of the
~luid adjacent to the second end 39 of the tilt cylinder 35. ;~
Under such circumstances, the pressure fluid flows past the
tilt piston 41 through the valve 61 from the second end 39 to
.
the first end 37 of the tilt cylinder 35 so as to permit such
` extension. As the pump 73 is not running, the control valve
piston 99 is centered and both valves 111 and 121 are closed.
During the period when the second end 39 of the tilt cylinder
35 is highly pressurized, such pressurization will be imparted
through the conduit 154 to open the valve 153 so as to permit -~
passage of a relatively small amount of highly pressurized
fluid therethrough to the first end 159 of the let-down valve
housing 157, which fluid is effective to displace the let-do~n
piston 171 from the first position to the second position.
Upon full extension of the tilt cylinder 35, the pressure con-
dition at the second end 39 thereof will be relieved and the
valve 153 will again closP preventing return of the pressure
fluid at the first end 159 of the let-down valve housing 157
` 30 through the valve 153 to the second end 39 of the tilt cylinder `~
35, thereby temporarily retaining the let-down valve piston 171
in the second position so as thereby to retain the valve 163 open.
.
. ; . . . ' ~ ~ ~ . . '
53~ 3
Upon reaching the fully raised position, the pro- ~ .
pulsion assembly 17 will tend to return downwardly either
because of impacting at the fully raised position or simply
because of the weight of the motor. Temporary maintenance
of the open condition of the valve 163 by the let-down valve
piston 171 permits contraction of the tilt cylinder 35 accom-
panying lowering of the propulsion assembly 17. In this
. regard, contraction of the tilt cylinder 35 causes outflow of
fluid from the first end 37 thereof, which outflow travels
through th~ conduit 165, through the valve 163 into the second
end 161 of the let-down valve housing 157 and through the
,~ conduit 175 back to the sump 71. At th~ same time, the ex-
` panding space at the second end 39 of the tilt cylinder 35 :.
i draws fluid from the sump 71 through the filter 91, and through
. 15 the conduit 177 including the one-way valve 179 to the second ::.
end 39 of the tilt cylinder 35 to maintain the second end 39 ~
of the tilt cylinder 35 fully occupied with hydraulic fluid. : .:
. Referring to the pressurized fluid trapped at the ~.first end 159 of the let-down valve housing 157, such fluid ..
. 20 gradually flows through the restricted orifice or slot 172 to
.i the second end 161 of the let-down valve housing 157 and then
:. through the conduit 175 to the sump 71. Such travel of the
~ . .
trapped fluid past the let-down piston 171 causes return move-
. ment of the let-down piston 171 toward the first end 159 of ~. .
the let-down valve housing 157 under the influence of the spring
.
.~ biasing the valve 163 to the closed position, thereby eventually ~ .
again permitting closing the valve 163 after completion of fluid ~:.:
. flow from the first end 37 of the tilt cylinder 35 to the sump .. .
~, 71. Thus, the hydraulic system 25 is again conditioned for ~ r
'.`i` 30 power operation, up or down, or for another impact.
.. ~ It is particularly noted that the trim piston 51
does not move during impact tilting or let-down return, and
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. .
:., ~ . . . , :
~L~5~3~)i33
thus the propulsion assembly 17 will always return after an
impact to the previously set trim position. It is also noted
that the pump 73 is isolated from the relatively high pressures
generated in the second end 39 of the tilt cylinder 35 by
sudden impact o~ the propulsion assembly 17 with an underwater
obstacle by reason o the centered position of the control
valve piston 99 and the closed condition of the valves 111 and ~
121. -
Various of the features of the invention are set
forth in the following claims. ~ :
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